diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 24775794..e2023421 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -13,7 +13,7 @@ class ApplicationController < ActionController::Base
 
   def current_user
     ::NewRelic::Agent.add_custom_attributes(external_user_id: session[:external_user_id], session_user_id: session[:user_id])
-    @current_user ||= ExternalUser.find_by(id: session[:external_user_id]) || login_from_session || login_from_other_sources
+    @current_user ||= ExternalUser.find_by(id: session[:external_user_id]) || login_from_session || login_from_other_sources || nil
   end
 
   def require_user!
diff --git a/app/controllers/sessions_controller.rb b/app/controllers/sessions_controller.rb
index 059c1888..145c3fd8 100644
--- a/app/controllers/sessions_controller.rb
+++ b/app/controllers/sessions_controller.rb
@@ -30,7 +30,7 @@ class SessionsController < ApplicationController
   end
 
   def destroy
-    if current_user.external_user?
+    if current_user&.external_user?
       clear_lti_session_data
     else
       logout